Older leaves turn yellow and die?

[Trespasser]

Hi,

I have 4 young Afghan seedlings growing in potting soil under fluorescent lamps indoors. They get NPK fertiliser with each watering, and only get watered after they dry out and begin to droop. The new growth is okay, but older leaves at the bottom of the plants turn yellow, dry up and drop off. The yellowing starts at the edges, then consumes the whole leaf.

Any ideas, anyone?

Regards,
Tressie

[Budbaron]

Originally Posted by Trespasser

Hi,

I have 4 young Afghan seedlings growing in potting soil under fluorescent lamps indoors. They get NPK fertiliser with each watering, and only get watered after they dry out and begin to droop. The new growth is okay, but older leaves at the bottom of the plants turn yellow, dry up and drop off. The yellowing starts at the edges, then consumes the whole leaf.

Any ideas, anyone?

Regards,
Tressie

your plants sound real young. how old are they? you say seedling then you shold not be feeding them any nutes. especially every watering. i am also quite sure that you should not let the plants start to droop before watering. there is a balance to be struck. this means watering before any drooping.

any pictures?

[Trespasser]

Hi Budbaron,

Yeah, i've been tending to think that the yellowing is maybe fertiliser related. The plants are at about 6-weeks, by the way. I've gone onto plain tap water without the fertiliser just to see what happens. It's too soon to tell what difference that will make. If it gets worse I'll try a different fertiliser. I wonder what type is good for indoors dirt farming? They've got fish emulsion in the local supermarket. It's exy, but.

Regards,
Tressie

[Trespasser]

Hi GC,

Oh, no! I tried changing fertiliser to fish emulsion, and now I have totally yellow leaves. I must have over fertilised. How do I fix this?

Regards,
Tressie

[Budbaron]

tresspasser

to be honest yellowing of the leaves, called chlorosis, is generally related to Nitrogen deficency. what are the N-P-K of your fertilisers? if you plants are 6 weeks old then they will need fertiliser, especiall the N. do you have a Ph meter? nutrient lockout happens when the Ph leves are out of optimal levels. next step is to check your Ph. although you have mentioned that they are completely yellow. in this case the plants are unlikely to live any longer as the green colour, which is the colour of chlorophyl, has gone. chlorophyl is the pigment and photosynthetic chemical found within the chloroplast organells of any plant. chloroplasts are the place or organells which produce energy or sugars for growth. chloroplasts like mitochondrian in animals produce the enery needed to live and so if they are gone, through chlorosis, the plant no longer has provisions to create it's own energy. i'm thinking Ph is maybe an issue. It is all a learning experience, check the Ph mate. and think about your next grow.

[Trespasser]

Originally Posted by Budbaron

tresspasser

to be honest yellowing of the leaves, called chlorosis, is generally related to Nitrogen deficency. what are the N-P-K of your fertilisers? if you plants are 6 weeks old then they will need fertiliser, especiall the N. do you have a Ph meter? nutrient lockout happens when the Ph leves are out of optimal levels. next step is to check your Ph. although you have mentioned that they are completely yellow. in this case the plants are unlikely to live any longer as the green colour, which is the colour of chlorophyl, has gone. chlorophyl is the pigment and photosynthetic chemical found within the chloroplast organells of any plant. chloroplasts are the place or organells which produce energy or sugars for growth. chloroplasts like mitochondrian in animals produce the enery needed to live and so if they are gone, through chlorosis, the plant no longer has provisions to create it's own energy. i'm thinking Ph is maybe an issue. It is all a learning experience, check the Ph mate. and think about your next grow.

Hi Budbarron,

Thanks for your very knowlegeable reply. Hmm...I ran tap water through the potting soil a couple of times, and the plants picked up a little. I'll have to do some research and figure out how to test soil pH. The tap water I've been watering with is pH 7.7, but I don't know if that's suitable. Yes, I've got some learning to do it seems.

Thanks very much for the helpful suggestions, Budbarron. I'll let you know how I get on.

Regards,
Tressie

[Trespasser]

Hi Budbarron,

Yep, without being able to test the actual soil pH, my guess it's a pH issue. The water I'm using is pH 7.7 and it seems I should be aiming for a slightly acid pH between 6.3 and 6.8. The nitrogen seems to be there in the fish emulsion at 50g/L, but wouldn't appear to have been taken up due to the high pH. I'll try adding some HCL to the watering can and see if I can't get that in range first. I guess we'll see what happens from there.

Thanks again for the advice. It's muchly appreciated.

Regards,
Tressie

[Budbaron]

Goodluck Tresspasser. if you want to test the Ph of your growing medium go to a garden centre and ask for a Ph metre for soil. i have even seen one time Ph checkers. you just take a little soil add water and some powder shake and you get you Ph by colour changes.